Intelligent Treadmill and Enhancements to Standard Treadmills

ABSTRACT

An intelligent treadmill is described with modifications to existing treadmills, and associated methodology. The invention allows the conveyor belt automatically keeps track of and fixes the user&#39;s position dynamically with respect to a stationery reference point of the treadmill by adjusting its own speed free hands. Two position measurement techniques and their corresponding belt speed control algorithms are described. Other features of the invention allow users to perceive in real time how their surroundings would be changing by means of video, incline of platform, fan speed, sound and illumination as if they were in fact running in the natural environment. Real time positions of the runner and his partners on other treadmills with respect to a chosen track are displayed. The invention also utilizes a vectored controlled 2/3-phase AC induction motor or a BLDC motor to drive the conveyor belt for energy efficiency and fast response.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/966,247 filed Feb. 20, 2014, which is incorporated herein byreference.

FIELD OF THE INVENTION

The present invention relates to a device for walking or running whilestaying in the same place, commonly referred to a treadmill,enhancements and adaptations to existing treadmills, and associatedmethodology. Specifically, the treadmill aspect of the inventioninvolves a modification to conventional drives found in domesticapplications, a position sensing device, a speed controlling algorithmto dynamically fix the user or runner at the same position and a virtualenvironment to aid walking and running with Internet based socialcommunication. In this document, the terms “user” and “runner” share thesame meaning, i.e. the human body moving on the moving belt of thetreadmill.

BACKGROUND OF THE INVENTION

Treadmills are popular exercise machines for running or walking in oneplace, usually indoors, including the home, school, fitness center, oreven office. The basic treadmill provides an adjustable slantingplatform on which a wide conveyor belt is running; the belt is driven byan electric motor through a sheave, usually Direct Current (DC) typedfor home treadmills, with a rating from 1.5 to 4 horsepowers.Commercially graded treadmills used in gyms may employ AlternatingCurrent (AC) motors. The conveyor belt moves in a way requiring therunner to walk or run at a speed matching that of the belt, which isusually adjustable but fixed. Here, “fixed” means that the speed iseither constant or undergoes a continuous acceleration or decelerationover a short period of time until the speed becomes constant. This isthe operation of common treadmills. The “fixed” rate at which the beltmoves can be controlled by the runner on a control panel to a continuousrate from a slow walk or to a run, which is displayed on the controlpanel.

Most treadmills have at least the following standard functions: (1)controllable but constant speed of movement of the belt; (2) inclinedsetting allowing for consistent “uphill” training; (3) features tomeasure and display the heartbeat of the user; (4) preinstalled programsfor simulating various exercise routines; (5) measurement of distancerun by the runner, estimation of calories burned, and other performancemeasurements such as average speed; (6) audio and/or visual input oroutput allowing runners to listen to music from an audio device oraudio-visual device, or both; (7) monitors allowing the user to viewtelevision, movies, or other visual materials; (8) a fan to blow airover the runner for cooling or to provide as if the runner were notstanding still; and (9) a mechanism to stop the machine under emergencyconditions when the runner moves to a rear position of the beltconsidered too unsafe for operation, such as a magnetic detector linkedto the runner via a piece of string with a clip on the runner's cloth.

Having introduced the standard functions of conventional treadmills, wenow turn to how conventional treadmills generally function and theproblems with the standard design. One purpose of a treadmill is toallow for exercise via running or walking inside and in one place. Oneadvantage of a treadmill over other exercise machines is the freedom ofmovement: it allows users walk or run as if they were not walking orrunning in place. In other words, treadmills allow users to walk or runin their natural strides, at the natural height in which they pick theirfeet up off the ground, move their hands freely as if they were notstanding in place, and other movements which other exercise machinesrestrict. Even though this freedom of movement aspect is realistic inthe sense runners would do the same if they were not standing in place,other features of how conventional treadmills shape the user experienceare unrealistic.

One important unrealistic aspect of treadmills is due to the operationof treadmills in terms of the constant speed setting. Users adjust thespeed of the conveyor belt manually, i.e., to change the speed usersmust consciously utilize an interface to adjust it. Once a new speed isset, the belt accelerates or decelerates gradually for a short period oftime until the new speed of the belt is achieved. The constant speedoperation imposes a strict pace on runners, perhaps giving an unnaturalfeel to running which can cause a runner to loose balance and feeldiscomfort. How the speed on standard treadmills is controlled isunrealistic because human beings do not naturally run under a constantspeed; rather, people naturally move faster and slower slightly overtime but usually the overall average speed, say in one hour, is almostconstant. However, during normal operation, treadmills prevent therunner to adjust even small changes in speed, unless with the runner'sconscious attention to key in a command on the control panel. In thisregard, although speed control by the runner is relatively easy andstraight forward, merely by requiring conscious effort to change speedeven slightly does not always offer the psychological satisfaction thatrunners get from running outdoors or anywhere where speed control doesnot have to be a conscious effort.

A second important unrealistic aspect of treadmills is perhaps due tothe problem treadmills attempted to solve in the first place: walking orrunning outdoor or indoor is unavailable. However, many treadmill userstoday use treadmills because of convenience—i.e., even when walking orrunning outside or somewhere inside is available. Nonetheless, the userexperience of conventional treadmills is unrealistic compared withwalking or running not-in-place because the runner is, by definition,not moving geographically and so the runner's surroundings are notchanging. This psychological consideration may at first seem irrelevantbecause of the fact that the runner is indeed not moving geographically,but despite the obviousness of not moving geographically on a treadmillmay take a toll on the runner's motivation and mental wellbeing at leastcompared to walking or running outdoor. One reason is that treadmillexercise does not allow runners to unconsciously compare their progressin the walk or run; instead, they must look to the treadmill's displayof distance or time to check their progress based on these figures only.One could compare this to a runner who typically walks or runs a numberof routes and thus knows the remaining distance or effort required tocomplete the desired exercise. The surrounding environment in such awalk or run allows the walker or runner to acquire mental estimationabout the remaining distance, whereby the walker or runner canunconsciously decipher the remaining difference. This cannot happen on atreadmill. This psychological consideration is yet another unrealisticaspect of conventional treadmills. In a similar vein, standardtreadmills are made for individual users—e.g., the belt is not wideenough, or designed, to allow two or more people walk or run on ittogether. Even if two runners walk or run side by side on adjacenttreadmills, the feeling of companionship and support achieved from it ismost likely less than by walking or running side by side in a naturalenvironment as they know the pace of the other person. This perceptionof relative pace setting and comparison is what is lacking fortreadmills, which perhaps can detract from one's motivation to exercise.

Having introduced the standard functions, general functioning, and a fewunrealistic aspects of the standard treadmill design, we will nowdiscuss the standard power drive and problems with it. Almost allexisting home-use treadmills use DC motors with a rated voltage from 12V to around 130 V. From a design standpoint, the speed and change inacceleration controls for DC motors are straightforward. Although DCmotors are efficient at changing conveyor belt speeds, they are notenergy efficient, not for swift acceleration or deceleration, and tendto require maintenance. Moreover, this technology is fading gradually inrelated machines. Current ratings for most standard home treadmill DCmotors are below 4 (continuous) horsepowers (or about 3 kW) with a peakrotating speed of around 4,000 r.p.m. Generally, DC motors used for hometreadmills are of the Permanent Magnet DC (PMDC) typed. The permanentmagnets are installed at the stator. The rotor receives controlled DCcurrent via commutators and brushes. The loss at the contacts betweenbrushes and commutators is high and the optimal energy profile of DCmotors cannot be controlled.

The present invention addresses the need to alleviate problems in bothconventional home and industrial treadmills including: (a) theunrealistic constant speed aspect of standard treadmills due torequiring users to consciously utilize an interface to adjust even minorchanges in speed; (b) the unrealistic user experience aspect of standardtreadmills in that (i) because the user's surroundings are not changing(and, when users are exercising with one or more other people, notchanging together in real time), users must consciously check theirprogress in the walk or run by viewing the display of distance or timeinstead of unconsciously knowing the percentage of the exercisecompleted or remaining; (ii) an unchanging user environment is not asmentally and emotionally stimulating as a changing environment; and (c)the relatively outdated and energy inefficient technology used to drivethe conveyor belt for home treadmills.

SUMMARY OF THE INVENTION

The present invention involves a novel intelligent treadmill,adaptations to existing treadmills, and associated methodology.According to an aspect of the invention, the intelligent treadmillcomprises the means of allowing the runner to automatically change theconveyer belt speed hands free, which can be done consciously orunconsciously. The hardware and algorithms involved are detailed in theinvention. Upon changing the speed, the runner still keeps a more orless fixed position in space related to the indoor environment where thetreadmill is placed. These means are in addition to the standard methodof changing belt speed, that is, by the standard controllable manualspeed settings or automatic exercise profiles. The automatic, hands freespeed changing aspect of the present invention helps alleviate theunrealistic constant speed aspect of standard treadmills, which requiresrunners to consciously utilize an interface to adjust even minor changesin speed.

According to another aspect of the invention, the intelligent treadmillalso comprises the means of allowing users to perceive in real time howtheir surroundings would be changing if they were in fact walking orrunning not-in-place. In addition, the intelligent treadmill aspect ofthe present invention comprises the means of simulating, communicating,and displaying the real time positions of two or more treadmill runnerson different treadmills within said perceived surroundings. In otherwords, two or more treadmill users can perceive not only how they areprogressing through the chosen surroundings; the present invention isalso capable of including the position of other treadmill users withinthe surroundings in real time. These two former aspects of the presentinvention create a more realistic treadmill user experience for a runnerto check his own or his running partners' progress by simply knowing thechosen surroundings.

According to another aspect of the invention, the intelligent treadmillalso comprises the means of automatically varying the incline, fanspeed, or other features on the treadmill to correspond to theconditions of the automated surroundings as well as for the comfort ofthe runner. By way of example only, imagine one course transitions froma hilly, wooded area to a flat beach. The intelligent treadmill mayautomatically adjust from an incline to zero incline based on thecurrent position of the runner along the simulated trail, have thecooling fan at low speed in the wooded area turned to high speed nearthe beach (e.g., the wooded area has little moving air while there is abreeze next to the beach), and adjust the brightness of illumination ofthe treadmill from dim to bright (e.g., the tree cover in the woodedarea blocks the sun while the sun is shining next to the beach). This isa kind of environmental background controls. According to another aspectof the invention, sound of bird singing can be played in the simulatedwooded area, and sound of sea waves near the simulated beach.

According to an aspect of the invention, the present invention comprisesa two or three phase AC induction motor, or a Brushless DC (BLDC) motorto drive the treadmill conveyor belt for better transient response aswell as higher energy efficiency. The unique advantage of AC inductionor BLDC motors in the context of the present invention is due to fastertransient belt speed changes as compared with conventional treadmills,i.e., the present invention allows for automatic, hands free changing ofthe conveyor belt speed based on the sensing hardware and algorithms ofthis invention. At the same time, energy saving can be achieved. Aprevious invention involves the use of ultrasound distance measurementbut the precision achieved was found not good enough for ourapplication. An aspect of the invention makes use of laser technologyfor dynamic position sensing of the runner on the running belt. Anotheraspect of the invention makes use of pairs of poles, equipped with laserbased obstacle sensors and installed by the two sides of the runningbelt, to detect the current position of the runner. One pair of polesinstalled at the rear of the treadmill helps to initiate an emergencystop when the runner falls back to such position. Due to this nature ofthe present invention, another aspect of the present invention comprisesstandard vectored control algorithms which utilize the relatively hightransient torque of such AC or BLDC motors. In other words, the AC orBLDC motors are much more suitable for sudden acceleration anddeceleration than the standard DC motors that have only one dimension ofcontrol, i.e. the DC current fed to the rotor. In this way, the responseof AC or BLDC motors is even more immediate to fit the runner'sperformance. Furthermore, BLDC motors have a much higher torque-to-motorvolume ratio, good for replacing traditional DC motors. In addition, ACand BLDC motors require less maintenance than standard DC motors used inconventional treadmills. Finally, the use of 3-phase AC or BLDC motorscan improve energy efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood with regards to the followingdescription, appended claims and drawings where:

FIG. 1 is a schematic representation of the structure of the intelligenttreadmill of the present invention;

FIG. 2 is a schematic representation of the mechanism of distancemeasurement of the intelligent treadmill of the present invention;

FIG. 3 is a schematic representation of the monitor display of theintelligent treadmill of the present invention;

FIG. 4 is a schematic representation of first embodiment of measureddistance by using laser reflector method of the intelligent treadmill ofthe present invention;

FIG. 5 is a schematic representation of second embodiment of measureddistance by using three pair of poles and equipped with two sets ofreflectors/receivers method of the intelligent treadmill of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1 of the drawings and in accordance with theprinciples of the invention, the intelligent treadmill comprises a touchscreen monitor (1), transmitter/receiver (2), motor (3), electronicdrive (4), control panel (5), reflector (6) and three pairs of poles(7), (8) and (9).

The said touch screen monitor (1) is equipped with a pair ofloudspeakers and a dimmable lamp, displaying the video of thesurrounding environment of an outdoor track, downloaded from theInternet and a simple map showing runner current position.

The said transmitter/receiver (2) is for distance measurement, whichemits and receives a laser beam to help estimate the exact distance ofthe reflector of the runner away from it.

The said motor (3) is a vectored controlled 2/3-phase AC or BLDC motorthat adjusts the speed of the conveyor belt to fix the runner at a moreor less constant distance from the transmitter/receiver or at adynamically stable and stationary position on the moving belt.

The said 2/3-phase AC or BLDC motor (3) is energized by an electronicdrive (4) which gets power from a standard single phase supply.

The said control panel (5) is to control the speed of the treadmill andhas additional control to adjust the speed of the conveyor belt to fixthe user at a more or less constant distance from thetransmitter/receiver (2) or at a dynamically stable and stationaryposition on the moving belt.

The said reflector (6) is worn on the waist belt of the runner, which isused to reflect the laser beam from the transmitter/receiver (2).

The said poles (7), (8) and (9) are installed on both sides of theplatform of the said treadmill equipped with laser based transmitters,receivers and/or reflectors.

Every pole of a pair is situated on either side of the belt and thewhole pair can move along the belt on rails underneath the platform onand below which the belt is moving. The initial positions of these polesare factory preset while the user can slightly adjust that of (8) and(9), but not (7). Without loss of generality, as an example, on pole (7)of one side, there are two transmitters/receivers, known as (7A) and(7B) ((A) being higher than (B) at about 300 mm and 150 mm respectivelyabove the belt surface). On pole (7) of the other side, at the samelevels, there are two reflectors, also known as (7A) and (7B). A laserbeam is projected from transmitters (7A) and (7B) on one side toreflectors (7A) and (7B) on the other side and then received byreceivers (7A) and (7B) on the same side of the transmittersrespectively. This arrangement equally applies to pole-pairs (8) and(9). Such six sets of transmitters/reflectors/receivers can detect anyblockage of the laser beam in the midst. According to an alternativeaspect, only the transmitters are installed on the poles of one sidewhile the receivers are installed on the poles of the other side. Inthis way, the reflector is omitted. Both designs serve the same purposeof detecting blockage of the laser beam in the midst.

Referring to FIG. 2, the drawing shows the mechanism of distancemeasurement. According to one aspect, a transmitter (2) continuouslyemits a laser beam which is reflected by a reflector (6) on the waistbelt of the runner and picked up by a receiver (2). In this way, theaccuracy of distance measurement is more precise because only theposition of the abdomen of the runner is of concern. Even the posture ofthe runner changes, the abdomen remains more or less at the sameposition. Once the exact position of the reflector (6) is estimated, theposition of the centre of gravity of the runner is calculated by addinghalf the thickness of the human body. The control algorithm as describedin the following description controls the speed of the motor (3) tobring the runner at a more or less fixed position dynamically related toany stationary part of the treadmill. According to another aspect ofposition measurement, FIG. 2 also gives the side view of the threeposition measurement poles (7), (8) and (9), each with twotransmitters/receivers and/or reflectors (A) and (B), depending on whichside of the treadmill is shown in the figure.

Referring to FIG. 3, the drawing shows the normal display on the monitor(1) when the runner is treading along a preset track with or withoutpartners, downloaded through the Internet, though other displays foruser's setting are available. On the left, a simple map showing thetrail is displayed with the starting/end point indicated. A dot, say redin color, indicates the instantaneous position of the runner while otherdots of different colors, indicate the instantaneous positions of hispartners as retrieved through the Internet. In this way, the runnerknows his current position as well as that of his partners. It's likeGPS navigation on the road map. Parameters including but not limited tothe instantaneous speed of the runner, average speed of the whole group,percentage of track completed, and time remaining to finish the wholetrack are displayed under the map. On the right, a video of thesurrounding environment of the trail, synchronous to the current speedand position of the runner, is displayed. If the runner runs faster, thevideo is played faster, and vice versa.

Referring to FIG. 4, the drawing shows how parameters are defined forbelt speed and dynamic runner's position control when a reflector (6) onthe waist belt worn by the runner is used to reflect the laser beam fromthe transmitter (2).

Referring to FIG. 5, the drawing shows how parameters are defined forbelt speed and dynamic runner's position control when no waist belt isneeded and position of runner is measured by the three pairs of poles(7), (8) and (9), each equipped with two sets of transmitters/receiversand/or reflectors (A) and (B).

Illustrative embodiments of the functioning of the invention aredescribed below. In the interest of clarity, not all features of anactual implementation are described in this specification. It will ofcourse be appreciated that in the development of any such actualembodiment, numerous implementation-specific decisions must be made toachieve the developer's specific goals, such as compliance withsystem-related and business-related constraints, which will vary fromone implementation to another. Moreover, it will be appreciated thatsuch a development effort might be complex and time-consuming, but wouldnevertheless be a routine undertaking for those of ordinary skill in theart having the benefit of this disclosure. The novel treadmill,adaptations to existing treadmills, and associated methodology disclosedherein boast a variety of inventive features and components that warrantpatent protection, both individually and in combination.

By way of examples only, a description of one embodiment of theautomatic, hands free conveyor belt speed changer, the real time andinteractive surroundings display, and associated methodology will bediscussed. The automatic speed changer aspect of the invention addressesthe unrealistic constant speed aspect of standard treadmills. Forstandard treadmills, users fix a belt speed which remains constant untilthe user modifies the speed manually. Only during the transition fromone fixed belt speed to another fixed belt speed that there is shorttermed acceleration or deceleration. Obviously, the user must maintain afairly constant velocity, i.e., if the user walks/runs too fast he willstep off of the belt in the front of the machine onto the footrestcovering the belt sheave/motor assembly underneath the control panel (5)or if he walks/runs too slow he will step off of the belt onto thefloor. However, under standard treadmills, the fact that the run-ablebelt length is longer than one's stride allows the runner maymomentarily slow or speed up his pace, which would move him toward oraway from the front of the treadmill from his previous location,respectively. Then, the user can either revert back to his originalspeed and stay in the new location on the treadmill or momentarily speedup or slow down to reposition himself back to the original location,respectively. Regardless, current treadmills only allow users to speedup or slow down momentarily in that the belt speed is constant (withmanual adjustment of the belt speed on rare occasions). An aspect of thepresent invention adjusts the belt speed automatically to fit therunner's desired change in velocity. For instance, if the runner beginsto run faster, the belt will move faster, and vice versa. The ultimatetarget is to bring the dynamic position of the runner to the middle ofthe treadmill even when his speed keeps on changing.

According to an aspect of the invention, the treadmill includes one ormore means of accurately measuring the distance between the runner andthe front of the treadmill or ensuring the runner is dynamically trappedbetween two pairs of measurement poles. By way of example only, theintelligent treadmill uses a laser transmitter and receiver pair (2)(called the locator) which are installed right below the control panel(5). The height of the locator is adjustable to suit the level of thereflector (6). A previous invention (U.S. Pat. No. 6,733,423 B1 datedMay 11, 2004) utilized an ultra-sound transmitter and receiver tomeasure the position of the runner on the running belt; that previousinvention claimed that once the position was estimated, the speed of thebelt could be adjusted. Upon implementing the methodology, threeproblems were found. First, ultra-sound waves hit the runner atdifferent spots and therefore the reflected waves indicated a mixture ofthe position of different parts of the runner's body, thus significantlydowngrading the accuracy. Second, the precision of ultra-sound distancemeasuring technology is well below the requirement which should bewithin a range of ±20 mm. Third, nothing on the speed control algorithmwas mentioned in that previous invention. The locator measures thedistance from itself to the runner's waist or other part of the runner'sbody equipped with a reflector (6), thus one single point of reflection.For instance, the user could wear a reflector on the middle front spotof the waist belt to reflect the laser beam. If accidentally thereflector (6) is out of sight from the laser team emitted by thetransmitter (2), the belt speed remains unchanged.

According to an aspect of the invention, the intelligent treadmillutilizes this one or more measured distances of the runner to change thespeed of the belt in order to fix the position of the runner dynamicallyat a desirable distance from a reference point on the treadmill, say atthe middle of the belt. The dynamic position control algorithm relatedto this type of distance measurement is as follows, with reference toFIG. 4.

X_(o) is the desirable permanent position of the runner, say at themiddle point along the moving belt, as measured from the lasertransmitter/receiver (2). The running speed of the runner is s(t), afunction of time t, with respect to the belt, not the indoorenvironment; the speed of the running belt is v(t), also a function oftime, under continuous control by the system based on the dynamicposition of the runner with respect to the indoor environment. Theinstantaneous horizontal distance between the centre of gravity of therunner and a stationery reference point right below the control panel(5) is given by x(t), also a function of time, which includes thedistance, l, measured by the laser transmitter/receiver (2) and half theassumed thickness of the runner, about 0.15 m. Such added value can bekeyed in by the runner.

The equation of dynamics is given by:

$\frac{x}{t} = \left( {v - s} \right)$

while the equation of the control algorithm is given by:

$\frac{v}{t} = {\left. {{- {K_{P}\left( {x - X_{o}} \right)}} - {K_{I}{\int{\left( {x - X_{o}} \right){t}}}}}\Rightarrow\frac{^{2}x}{t^{2}} \right. = {{\frac{v}{t} - \frac{s}{t}} = {{- {K_{P}\left( {x - X_{o}} \right)}} - {K_{I}{\int{\left( {x - X_{o}} \right){t}}}} - \frac{s}{t}}}}$

Here, K_(p) and K_(I) are two factory pre-tuned positive real numberswhich are the proportional gain and the integral gain respectively.Since s is arbitrarily varying due to the runner, this differentialequation can only be solved once s is known with a goal to make∥x−X_(o)∥² as small as possible. Having said that, the equation

$\frac{v}{t} = {{- {K_{P}\left( {x - X_{o}} \right)}} - {K_{I}{\int{\left( {x - X_{o}} \right){t}}}}}$

is good enough to facilitate the speed control action because x ismeasurable while all other parameters on the right handed side of theequation are known. An emergency stop is actuated when x(t) goes beyonda limit, indicating that the runner has been too close to the end of themoving belt.

Even a laser distance measuring system is used, the accuracy is stillimprecise and sometimes non-deterministic because the posture of therunner keeps on changing on the belt. Also, it is easy that thereflector (6) cannot receive the laser team and is out of sight of thereceiver (2). Hence, the measured x cannot accurately indicate the exactposition of the centre of gravity of the runner.

In another aspect of the invention, the dynamic position of the runneris precisely kept within a confined spatial segment above the movingbelt determined by two pairs of obstacle sensing poles (8) and (9) asshown in FIG. 5. Another pair of obstacle sensing pole (7) is for safetyprecaution as it indicates the end of the belt. The exact position ofthe poles is pre-designed but the runner can slightly adjust that of (8)and (9), but not (7). As shown in FIG. 1, obstacle sensing poles come inpairs, one on either side of the moving belt and they could be movedtogether along the belt on rails below the platform. On each pair ofpoles, one on either side of the belt, there are two lasertransmitters/receivers on one side and two laser reflectors on the otherside, (A) and (B) respectively. An alternative design does not involvethe reflector, while transmitters (A) and (B) are on one side andreceivers (A) and (B) are on the other side. Without loss of generality,a laser beam is projected from a transmitter (9A) on one side to areflector (9A) on the other side, reflected back and received by areceiver on the transmitter side (9A). (9B), (8A), (8B), (7A) and (7B)work similarly. A flag which is binary, either “1” or “0”, is assignedby the control microprocessor to indicate whether anytransmitter/reflector/receiver combination of a pole is blocked by anobstacle in the midst, e.g. the flag of (9B)=“1” when blocked or =“0”when clear. For this particular application, the obstacle that blocks iseither the shoe, the foot or the leg of the runner because (A) is onlyless than 300 mm and (B) 150 mm above the moving belt. The dynamicposition control algorithm for this setup is as follows, reference madeto FIG. 5 again. Under this control algorithm, during operation, therunner is dynamically trapped in a spatial segment above the moving beltbetween pole pair (8) and pole pair (9), irrespective of his posture.

Pole pair (9) is at a horizontal distance X_(f) (f means front) from areference point, say at the front rotating sheave of the belt rightbelow the control panel (5). Pole pair (8) is at distance X_(r) (r meansrear) from the same reference point and Pole pair (7) is at a distanceX_(e) (e means end) from the same reference point. The desirable dynamicposition of the runner is still at X_(o) from the reference point asshown in FIG. 4, which is in the middle between X_(f) and X_(r). X_(f)is factory pre-adjusted to about X_(o)−0.3 m and X_(r) to X_(o)+0.3 m,bearing in mid that the runner can slightly adjust that. However, X_(e)marks the end of the belt, which cannot be adjusted. Again, v(t) is theinstantaneous speed of the moving belt under control and it obeys thefollowing control algorithms in Table 1. The binary flags are checkedwithin a time period of one complete control cycle taken by the belt totravel twice a distance of (X_(r)−X_(f)), thus dependent on the speed ofrunning belt, v. One complete control cycle is the average total timespent by two strides completed by the left and right feet of the runner,equal to one cycle of walking or running on the belt. For example, ifthe factory preset positions of (8) and (9) are unchanged, they areabout 0.6 m apart, and the time period of one control cycle is thenequal to 1.44 second if the instantaneous belt speed is 3 km/hr. Once aflag is equal to “1” at anytime within the control cycle, it is assigneda value of “1” for the whole control cycle. And the control action isdetermined and executed at the end of every control cycle, after whichall flags are automatically reset to “0”.

In Table 1, K_(I) bears the same meaning as the factory pre-tunedpositive parameter which is the integral gain; C₁ is the acceleration ofthe belt (positive or negative) at the beginning of the current controlcycle; C₂ is the moving belt speed of the current control cycle.

TABLE 1 Action at the Equivalent beginning of Action for the Flags of 7:A Flags of 8: A Flags of 9: A next control next control and B and B andB cycle cycle All “0” All “0” Either one “1”$\frac{dv}{dt} = {K_{I}{\int{dt}}}$$\frac{dv}{\text{dt}} = {{K_{I}t} + C_{1}}$ All “0” Either one “1”Either one “1” $\frac{dv}{dt} = 0$ v = C₂ All “0” All “0” All “0”$\frac{dv}{dt} = 0$ v = C₂ All “0” Either one “1” All “0”$\frac{dv}{dt} = {{- K_{I}}{\int{dt}}}$$\frac{dv}{\text{dt}} = {{{- K_{I}}t} + C_{1}}$ Either one “1” WhateverWhatever v = 0 Maximum deceleration to a safe stop

One feature of the present invention allows for and utilizes the factthat the runner basically maintains a more or less fixed spatialposition relative to the treadmill when the transmitter/receiver (2) isutilized. According to an aspect of the invention, the intelligenttreadmill can learn this desired operating position, by way of exampleonly, via the controller during the parameter setting stage when therunner is running on the moving belt under a constant speed. Thecontroller then knows where the runner feels comfortable on the movingbelt. Or the user can slightly and manually adjust the positions of thetwo pole pairs (8) and (9) to change the exact spatial segment to whichthe runner's position is dynamically confined. To expand on one exampleabove, when the treadmill is turned on, it runs at a constant speed andit takes, say, half a minute for the treadmill controller to learn thecomfortable position of the runner when obstacle sensing pole pairs arenot utilized. Then, the treadmill will go to the automatic speed ordynamic position control mode where the position of the runner isdynamically fixed at a distance from the transmitter (2) and an“automatic speed control” indicator is lit up on the control panel (5).If the obstacle sensing pole pairs are active, no such tuning isnecessary.

According to an aspect of the invention, the treadmill includes themeans of automatically stopping the conveyor belt in a short period oftime, whether it is for emergency or other reasons. By way of exampleonly, it is contemplated that the automatic stopping means utilize theactivation of any one of two obstacle sensing devices on pole pair (7),in combination to or separate from other means, thus fully replacingstandard function (9) of a conventional treadmill as mentioned before.

In this invention, motors (3) for home treadmills will either be2/3-phase AC induction motors or BLDC (brushless DC) motors, with arated capacity up to 3 kW though in real operation, they are usually notfully loaded with the help of vector controlled PWM (pulsed widthmodulation) voltage pulses while a high efficiency can be maintained.Vector controlled PWM voltage and current control can ensure andimproved transient response of speed control and energy efficiency.Electrically, there is no difference between a 2-phase AC motor and a3-phase AC motor when either one is driven by a PWM based VariableVoltage and Variable Frequency drive.

According to an aspect of the invention, the intelligent treadmill hasthe means of allowing the user to connect to, download, and upload databetween the treadmill and other computer devices, data storage devices,the Internet (either wireless or wired), or other ways of transferringand receiving data. By way of example only, one scenario of thefunctioning of the treadmill will be discussed. It is appreciated thatthis is only one example of an embodiment of the present invention,which only includes a number of applications of the features of thepresent invention. The treadmill includes the provision of a “mobileapp” on a standard smart phone. Video clips of popular trails or tracksof the natural environment with beautiful scenery are provided anddownloaded onto the smart phone which is connected to the Internetthrough Wi-Fi or data through cell phone carriers and to the controlpanel (5) through Bluetooth or Wi-Fi. When the runner is running on thebelt, the surrounding environment keeps on changing, synchronous to hisown pace, controlled to fit by the belt speed, and is displayed on themonitor (1) as if he were running on the real natural environmentaltrack outdoor. This is like the on-site navigation service provided onthe Google map. By the side of the video, the track is shown on a smallmap while the current position of the runner is highlighted by aparticular symbol, say a red dot. Under the map, information includingbut not limited to information such as current average speed of runner,average speed of the group, percentage of track completed by the runnerand estimated time to finish the whole track under the current speedetc. are displayed. In this way, the runner can know where he is atpresent and see the natural environment at this particular position ofthe real track. If he runs faster or slower, the video and the symbol onthe map will match in synchronism. The algorithm is described asfollows.

The video of treading the track of the natural environment is filmed bya mobile camera of the service provider under a constant speed ofmovement, V_(f), say 0.5 m/s, using a constant frame rate, fr, say 25frames per second, as examples, but there could be other choices ofV_(f) and fr. The position, p, a real number in meters, of the runner onthe simulated track at any instant, t, as experienced by the runner isestimated from the starting point of the track when t=0 second, i.e. thetime when the runner starts to tread on the treadmill. If theinstantaneous treading speed of the runner on the treadmill, s(t) almostequal to v(t) based on the control algorithms of this invention, isknown and recorded, p(t) is estimated to be:

p(t) = ∫₀^(t)v t.

Since the video was filmed by a mobile camera under constant speed,V_(f), each frame on the video corresponds to a particular position onthe track because advancing one frame on the video implies advancing thetrack by V_(f)/fr meters. In this case, p(t) actually relates to(p*fr)/V_(f), rounded to the nearest integer, which is the current framenumber on the video. Such frame number is also equivalent to the videotime code of a linear time code format. The controller of the treadmillkeeps on tracking v(t) and thus p(t) and hence the number of frameselapsed since the beginning when t=0 s. If L is the total length of thewhole track, current percentage finished by the runner as shown belowthe map on the monitor (1) is calculated by (p/L)*100%. It is this valuep(t) that is used by the control system of the treadmill as a tag toadvance the video and change the environmental background, such as slopeof treadmill platform, music, speed of circulating fan, and illuminationetc., synchronously as experienced by the runner with reference to thefollowing table, Table 2, which is downloaded from the “mobile app” fora particular track. Table 2 includes those parameters for environmentalbackground controls.

TABLE 2 p % slope or tilting frame number music level of speed of in ofangle of tread- or time code or illumi- circulating m L mill platform onvideo sound nation fan (%) file

Basically, the playing speed of the video is synchronous with v(t),given by: [v(t)/V_(f)]*[normal playing speed equal to the filmingspeed], while the exact instantaneous scene of the video is synchronouswith p(t).

Since the whole system is Internet connected, according to an aspect ofthis invention, the runner can invite partner(s) to run or jog on thesame track as involved in one exercise. All involved could see similarvideo but the exact scene depends on the instantaneous position of eachindividual runner along the agreed track. In other words, each runnerinvolved in the exercise has his own p(t). And all of them could seetheir exact positions on the map by the side with different symbols, saydots of different colors as examples. This is because different p(t) ofdifferent runners are exchanged through the Internet so that thecontroller of every treadmill knows the exact p(t) of every other runnerinvolved in the exercise, in addition to the local runner. Theinstantaneous position p(t) of each individual runner is calculated bythe speed of belt synchronous to the varying running speed of eachindividual runner while the environmental background control issynchronous with each individual runner. The only parameters that areexchanged between the treadmill controllers of different runners are thevarious p(t) of different runners. In this way, those running slowercould speed up or slow down to catch up with other partners and viceversa.

At the same time, they can talk to one another through the smart phonesor the Internet and a background sound and music of that environment isplayed to improve the fidelity based on the data file as shown in Table2 downloaded from the “mobile app”. Runners virtually at the same spoton the simulated track enjoy the same background, including but notlimited to tilting angle of the belt, sound or music file, level ofillumination and the speed of the circulating fan. But runners who havefinished different percentage of the track experience different videoand background. Sound from the loudspeakers of the monitor (1) and speedof the circulating fan on the control panel (5) are adjusted accordinglyto reflect the environment shown by the video. Tracks are updated fromtime to time by the service provider so that the scenery of differentseasons of the same track is available for downloading to enhance thetreading experience of the runner and his partners. The tilting angle ofthe platform and the running belt of the treadmill is continuouslyadjusted according to the instantaneous position of the track whichsimulates the real natural environment. In this way, the runner has anup-climbing experience when the track is leading to a hill. Subject tothe existing limitation of treadmill design, the tilting angle can atmost be lowered to zero degree, i.e. horizontal. In the future, newtreadmill design may include a down tilting angle to fit the simulatedtrack.

Although the present invention has been described in considerable detailin reference to preferred versions, other versions are possible.Therefore, the spirit and scope of the appended claims should not belimited to the description of the preferred versions contained herein.

What is claimed is:
 1. An intelligent treadmill allowing the conveyorbelt automatically keeps track of and fixes the runner positiondynamically with respect to a stationary reference point of thetreadmill by adjusting its own speed free hands based on speed varyingalgorithms, the said intelligent treadmill comprising: a touch screenmonitor, transmitter/receiver, motor, electronic drive, control panel,reflector and three pairs of poles, the said touch screen monitorequipped with a pair of loudspeakers and lamp, displaying the video ofthe surrounding environment of an outdoor track, downloaded from theInternet and a simple map showing current position of runner, the saidreceiver for distance measurement emitting and receiving a laser beam tohelp estimate the exact distance of the reflector on the said runneraway from it, the said motor which is a vectored controlled pulse widthmodulation based two or three phase alternating current or brushlessdirect current motor to adjust the speed of the conveyor belt to fix thesaid runner at a more or less constant distance from thetransmitter/receiver or at a dynamically stable and stationary positionon the moving belt, the said motor which is energized by an electronicdrive which gets power from a standard single phase supply, the saidcontrol panel which controls the speed of the treadmill and hasadditional control to adjust the speed of the conveyor belt to fix thesaid runner at a more or less constant distance from thetransmitter/receiver or at a dynamically stable and stationary positionon the belt, the said reflector worn on the waist belt of the saidrunner for reflecting the laser beam from the said transmitter/receiver,the said three pairs of poles installed on both sides of the platform ofthe said treadmill equipped with laser based transmitters, receivers andreflectors.
 2. The intelligent treadmill of claim 1 wherein said meansfor measuring instantaneous position of the said runner of the saidtreadmill comprise a laser based transmitter and receiver installed atan appropriate position of the said treadmill, and a reflector worn onthe body of the said runner.
 3. An intelligent treadmill of claim 1wherein said means for measuring instantaneous position of the saidrunner comprise several pairs of poles installed on both sides of thesaid platform of the said treadmill at appropriate positions, equippedwith laser based transmitters, receivers and reflectors for detectingthe existence of any obstacle between two corresponding said poles. 4.An intelligent treadmill of claim 2 wherein said a speed varyingalgorithm of the conveyor belt of the said treadmill based on the saidposition of said runner measured of claim 2 is according to a set ofdifferential equations with tuned gains, K_(I) and K_(P), forautomatically and dynamically fixing the said position of said runner ata desirable position on the moving belt with reference to a stationarypoint of the said treadmill.
 5. An intelligent treadmill of claim 3wherein said a speed varying algorithm of the conveyor belt of the saidtreadmill based on the said position of said runner measured of claim 3is according to a set of differential equations with tuned gains, K_(I),C₁ and C₂, for automatically and dynamically fixing the said position ofsaid runner at a desirable position on the moving belt with reference toa stationary point of the said treadmill.
 6. An intelligent treadmill ofclaim 3 and claim 4 wherein an emergency stopping procedure stops themoving belt when either the said position of claim 3 or the saidposition of claim 4 exceeds a safety limit.
 7. An intelligent treadmillof claim 1 wherein said means for keeping track of the instantaneousposition of the said runner with respect to the said outdoor track forsynchronization of the video display and environmental backgroundcontrols, means for continuously updating the said position of the saidrunner along the said track based on the said speed of the conveyor beltfor displaying the corresponding scene of the surrounding environment ofthe said track, the said position of the runner on a map of the saidtrack and parameters on the said monitor, and means for providingenvironmental background control at the local said treadmill includingincline of said platform, music and sound, speed of circulating fan on acontrol panel of the said treadmill, and the level of illumination, areprovided.
 8. An intelligent treadmill of claim 1 wherein said means forintercommunicating the instantaneous positions of said runners ondifferent said treadmills using the same outdoor track for displayingthe updated positions of all said runners on the said monitors, allowinga group of said runners running on their corresponding said treadmills,exchanging instantaneous positions of said runners, and displayingpositions of all said runners of the said group on the map of commonsaid outdoor track on all said monitors.